Platform for stereoscopic image acquisition

ABSTRACT

There is disclosed a method and apparatus for acquiring stereoscopic images. A first camera may be mounted to a first convergence plate, the first convergence plate coupled to a first plate via a first XY slide and a first pivot displaced from the first XY slide. A distance between the first plate and a second plate may be adjusted to set an interocular distance between the first camera and a second camera. The first convergence plate may be rotated about the first pivot to set, at least in part, an angle of convergence between the first camera and the second camera.

RELATED APPLICATION INFORMATION

This patent claims priority from non-provisional patent application Ser.No. 11/422,048, filed Jun. 2, 2006, entitled PLATFORM FOR STEREOSCOPICIMAGE ACQUISITION now U.S. Pat. No. 7,643,748.

BACKGROUND

1. Field

This disclosure relates to stereoscopy.

2. Description of the Related Art

Humans view the environment three-dimensionally using binocular vision.Binocular vision is both a visual system and an analytical system. Ourbrain perceives both distance and speed based, in part, on triangulatingvisual light information received by the retinas of our respectivelaterally separated, forward facing eyes. Since both eyes are forwardfacing, the field of view overlaps with each of our eyes having aslightly different perspective of the same area. As we focus on objectscloser to our eyes, our eyes rotate towards each other, increasing theangle of convergence. As we focus on objects afar, our eyes rotatetowards a parallel view, decreasing the angle of convergence.

Three dimensional imaging, also known as stereoscopy, dates, at least,as far back as 1838. Cinematographers frequently mount two lenseslaterally apart a similar distance as an average human's eyes,approximately 65 mm. The effective distance of the lenses from eachother is known as interocular distance.

Stereoscopic projection generally includes projecting two distinctimages, one representing a view from the left eye and the otherrepresenting a view from the right eye. With regard to the silverscreen, the illusion of depth has been effected via polarization,filters, glasses, projectors, shutters and arrays.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevated plan view of a platform.

FIG. 2 is an underside plan view of a platform.

FIG. 3 is an exploded elevated plan view of a platform.

FIG. 4 is an elevated plan view of a plate.

FIG. 5 is an elevated plan view of a plate.

FIG. 6 is an elevated plan view of a convergence plate.

FIG. 7 is an elevated plan view of a camera mount.

FIG. 8 is an exploded side view of a platform.

FIG. 9 is an exploded rear view of a platform.

DETAILED DESCRIPTION

Throughout this description, the embodiments and examples shown shouldbe considered as exemplars, rather than limitations on the apparatus andmethods disclosed or claimed.

Description of Apparatus

Referring now to FIG. 1, there is shown an elevated plan view of aplatform 100. The relative position of various parts of the platform 100will be described based upon this view. For example, terms such as top,bottom, left and right are used. However, the platform 100 may be usedin various positions such as upside down. Thus, some descriptive termsare used in relative terms and not absolute terms. The platform 100 maybe a prop adapted for use in stereoscopic image acquisition. Theplatform 100 may include rigid components and provide mechanical supportto digital cinema equipment. The platform 100 may be a device adapted tohold and/or move parts, such as still cameras, video cameras, or otherimage acquisition devices in or to a predetermined position.

Examples of image acquisition devices include charged coupled devices,complementary metal-oxide semiconductor (CMOS) devices, film and otherdevices. Image acquisition devices may acquire visual information singlyor in sequence as in motion video.

The platform 100 includes a base 110 having a first plate 120 and asecond plate 130 attached via a linear slide 140. The platform 100includes a first convergence plate 150 attached to the first plate 120via a first pivot 185 and a first compound crossed roller slide 160. Theplatform 100 includes a second convergence plate 170 attached to thesecond plate 130 via a second pivot 186 and a second compound crossedroller slide 180.

The platform 100 may be constructed of materials that havecharacteristics of high strength, light weight and high rigidity.Examples of such materials include aluminum, titanium, and magnesiumalloys. The platform 100 may be of small relative size so that robuststeel alloys may be utilized for low cost manufacturing.

The platform 100 may include a first camera mount 181 that may attach toa top surface 183 of the first convergence plate 150. The platform 100may include a second camera mount 182 that may attach to a top surface184 of the second convergence plate 170.

As shown in the top side view of FIG. 1, the platform 100 may include aleft side 190, a right side 191, a rear side 192 and a front side 193.As shown in the underside plan view of the platform 100 in FIG. 2, theplatform 100 may include a mounting device 210. The mounting device 210may be adapted to attach the platform 100 to a support (not shown). Thesupport may be a tripod, a steadicam, a crane, a boom, underwaterhousings, custom pan and tilt armatures, helicopter mounts, euromounts,or other device that may support a platform 100 for use in stereoscopiccinematography. A steadicam may have a maximum load capacity ofapproximately 45 pounds. Thus, with regard to use with a steadicam, alightweight platform 100 may be utilized. Because the platform 100 maybe attached to a variety of stationary or moveable devices, the platform100 may be used in myriad positions, and have the front 193 facing anydirection. The platform 100 may be adapted to allow an image acquisitiondevice to receive images that beyond the front 193 of the fixture 100.

The base 110 is a structure to which operating parts of a system may beattached. The base 110 may be formed from a unitary object or may be anassembly of components. The base 110 may be symmetric or asymmetric.

Referring now to the exploded elevated plan view of a platform 100 inFIG. 3, the elevated plan view of a platform in FIG. 4 and the elevatedplan view of a platform in FIG. 5, the second plate 130 includes alinear slide 140. The linear slide 140 may be adapted to allow thesecond plate 130 to be displaced laterally relative the first plate 120.

The linear slide 140 may provide structural support and stability to thesecond plate 130 from the first plate 120. The linear slide 140 may beadapted for precise, high speed linear motion. The linear slide 140 mayhave characteristics including a low coefficient of friction and lowacoustic output. In turn, the linear slide 140 may be characterized bysmooth, noiseless motion. Additionally, the linear slide 140 may resistmoments, such that the second plate resists roll and tilt. Tilt refersto angular displacement about the longitudinal axis of a device. Rollrefers to rotation about the longitudinal axis of a device.

Common examples of linear slides include shaft guidings, profile railguides, cam-roller guides, precision rail guides, miniature slides andstandard slides. The selection of the linear slide 140 may be based onthe load it must support, the acceleration and velocity it will besubjected to and the resistance to roll and tilt the linear slide 140must provide. For example, in precision cinematography, the linear slide140 may be a precision rail guide or a crossed roller slide. Forstability enhancement, plural linear slides 140 may support the secondplate 130 via the first plate 120. As shown in FIG. 3, the linear slide140 includes two rails in parallel. By utilizing a plurality of rails,lateral motion of the second plate 130 relative the first plate 120 islimited to motion within a plane.

The first plate 120 and the second plate 130 may each be a platform, apermanent or temporary mounting member. The first plate 120 and thesecond plate 130 may each have a geometry of a general rectangularsolid. Additional embodiments may include a first plate 120 and a secondplate 130 having geometries of a triangular solid or other regular orirregular geometry. The first plate 120 and the second plate 130 may besymmetric or asymmetric in shape. The smaller the second plate 130 is,the less load that the linear slide 140 will be required to support.

The first plate 120 may include a section 410 (FIG. 4) adapted to engageor be integrated with the first compound crossed roller slide 160(described in further detail with regard to FIG. 8 and FIG. 9 below).The term engage refers to coming into contact with or interlocking witha device. The section 410 may include a single or plural rails orguides. The selection of the number of rails or guides may be based onthe stability required for the application of the platform 100. Theexample shown includes two guides 411, 412 assembled to the section 410.The selection of parallel guides aid in restricting the first compoundcrossed roller slide 160 to planar motion. Similarly, the second plate130 may include a section 510 adapted to engage or be integrated withthe second compound crossed roller slide.

The first plate 120 and the second plate 130 may respectively have adepression or hole 420 and 520. The depressions 420 and 520 may beadapted to receive the first pivot 185 and a second pivot 186,respectively. The depressions 420 and 520 may include a polished surfacehaving a low friction coating, for example, wax orpolytetrafluoroethylene. Pivots are devices, typically with a geometryof a shaft, a ball or a pin, about which members rotate. The holes 420and 520 may be offset from the sections 410 and 510 a predetermineddistance in order to select a radius for rotation of cameras (not shown)or other image acquisition devices. The first pivot 185 and the secondpivot 186 may include elements, such as a threaded shaft and collar,which aid in the alignment of the convergence plates 150 and 170.

The first plate 120 and the second plate 130 may respectively have agroove 430, 530. The grooves 430 and 530 may be configured in apredetermined arc, linearly, or other irregular path. The grooves 430,530 and/or the pivots 185, 186 may be utilized to guide motion forcameras (not shown) or other image acquisition devices.

The convergence plates 150, 170 each may be a rigid member adapted tosupport an image acquisition device. The convergence plates 150, 170 mayhave a geometry which includes a generally flat top surface. Theconvergence plates 150, 170 may include respective surfaces 183, 184adapted to affix to the convergence plates 150, 170 either a respectivemounting device 181, 182 or an image acquisition device (not shown).

Referring now to the elevated plan view of FIG. 7, there is shown amounting device 181. A camera (not shown) may be mounted to the mountingdevice 181 to enable quick and easy mounting to the top surface 183 ofthe convergence plate 150. Image acquisition devices may be mounted tothe mounting device 181 via fasteners, magnets, or adhesives. Imageacquisition devices may be integrated with the mounting device 181.

In the film industry, quick precision swapping of cameras is a costfactor that effects profitability. The mounting device 181 may includeone or a plurality of holes 710 or openings 720 to which fasteners maybe utilized to affix a camera. The mounting device 181 may also includeedges 750, 760 which may be scalloped, flat, or have a regular orirregular geometry adapted for specific mounting applications.

Referring again to FIG. 1, the surfaces 183, 184 of the respectiveconvergence plates 150, 170 may be scalloped, flat, or have a regular orirregular geometry adapted for a specific mounting device. The termscalloped refers to a wavy edged geometry. Based on the geometry of themounting devices 181, 182 and the respective convergence plates 150,170, the mounting devices 181, 182 may be either slid onto therespective convergence plates 150, 170 or set down perpendicularly ontothe respective convergence plates 150, 170. This may allow for the quickswapping of image acquisition devices in tight spaces.

In turn, the convergence plates 150, 170 may be able to better preventan image acquisition device (not shown) from rolling or tilting whilethe second plate 130 is moving laterally from the first plate 120 and/orthe convergence plates 150, 170 are sliding and/or rotating.

The compound crossed roller slides 160, 180 may provide substantialmechanical support both to the convergence plates 150, 170, the mountingdevices 181, 182 and the image acquisition devices (not shown). Thecompound crossed roller slides 160, 180 are respectively attached to therespective convergence plates 150, 170 and the respective plates 120,130. The compound crossed roller slides 160, 180 may be attached to therespective convergence plates 150, 170 by a bearing, pin or otherpivoting or rotating device that allows the convergence plates 150, 170to rotate while traveling in a predetermined plane. The term compoundrefers to precision combination of generally perpendicular crossedroller slides enabling displacement and/or rotation within a singleplane. Examples of a compound crossed roller slide include an XY slideand an XY stage. The compound crossed roller slides 160, 180 may includea plurality of rails and bearings to enable stability and resistance tomotion outside of a predetermined plane.

Substantial mechanical support refers to a large degree or main portionof mechanical support. For example, when the platform 110 is in motionand/or the second plate 130 is moving laterally from the first plate 120and/or the convergence plates 150, 170 are sliding and/or rotating, themass of the image acquisition devices (not shown) in combination withthe convergence plates 150, 170 may exert moments which tend to causethe image acquisition devices to roll or tilt. The compound crossedroller slides 160, 180, by providing substantial mechanical support fromthe plates 120, 130 to the convergence plates 150, 170 and imageacquisition devices may limit the motion of the image acquisitiondevices to remain within a single plane.

By virtue of the attachment, engagement or integration between thecompound crossed roller slides 160, 180, the respective convergenceplates 150, 170 and the plates 120, 130, the convergence plates 150, 170are able to support image acquisition devices through a variety ofmotions, including 360 degree roll, tilt and yaw. Thus, even when upsidedown or at creative angles, the platform 100 restricts the motion of theconvergence plates 150, 170 to a plane.

Referring now to FIGS. 5, 8 and 9, there are shown an exploded side andrear view of a platform, respectively. The platform 100 may include afirst motor 810, a second motor 820 and a third motor 830. The firstmotor 810 may be mounted to the first plate 120. The second motor 820may be mounted to the second plate 130. The third motor 830 may bemounted to the first plate 120.

The first motor 810 may be adapted to rotate and/or displace the firstconvergence plate 150. The first motor 810 may cause the firstconvergence plate 150 to move via a rack and pinion, via a gear set, viaa belt, via a lead screw, via the compound crossed roller slide 160 orother displacement methods. Similarly, the second motor 820 may beadapted to rotate and/or displace the second convergence plate 170. Themotors 810 and 820 may cause the convergence plates 150, 170 to rotateand/or displace symmetrically.

Rotation and/or displacement of the convergence plates 150, 170 mayenable image acquisition which may be utilized to create an illusorystereoscopic experience. For example, when the first convergence plate150 is rotated counter-clockwise about the first pivot 185 and thesecond convergence plate 170 is rotated clockwise about the second pivot186, the angle of convergence is decreased. The resulting effect is oneof shifting stereoscopic depth of field from a close position to a farposition.

Conversely, when the first convergence plate 150 is rotated clockwiseabout the first pivot 185 and the second convergence plate 170 isrotated counter-clockwise about the second pivot 186, the angle ofconvergence is increased. The resulting effect is one of shiftingstereoscopic depth of field from a far position to a close position.

The third motor 830 may cause the second plate 130 to displace laterallyrelative the first plate 120. When the second plate 130 is shifted awayfrom the first plate 120, the interocular distance between the imageacquisition devices (not shown) mounted to the convergence plates 150,170 is increased. The resulting effect is one of developing a greaterstereoscopic depth of field. Conversely, when the second plate 130 isshifted towards the first plate 120, the interocular distance betweenthe image acquisition devices (not shown) mounted to the convergenceplates 150, 170 is decreased. The resulting effect is one of developinga lesser stereoscopic depth of field.

The motors 810, 820 and 830 may be controlled manually, viapredetermined computer algorithms, or a combination of both. Forexample, formulas may associate convergence angle and/or interoculardistance with an object focused on. Moreover, the cameras (not shown)mounted to the convergence plates 150, 170 may be different cameras orhave different characteristics in order to define a creative experience.Selection of the interocular distance and convergence angle are definingcharacteristics, the creativity which enables a lucid stereoscopicillusion.

The motors 810, 820 and 830 may be DC motors, servo motors, brushlessservo motors or other motors. Servo motors are designed to control highspeed and high power movements via error-sensing feedback. Servo motorsenable high accuracy in positioning. Servo motors have characteristicsof low friction, high speed, precision and low inertia Brushless servomotors have characteristics of longevity, low acoustic or audible noiseoutput and low electromagnetic output. Electromagnetic output may causeradio frequency interference which cause other electronic devices, suchas image acquisition devices, to malfunction and/or yield errors. If themotors 810, 820 and 830 yield low acoustical and electromagnetic output,then less post processing of the image and/or audio acquisition will berequired for an audio visual work of art. Post processing tends to bevery expensive.

The platform 100 described herein provides for light weight, compactportability, ease in packaging, ease of setting up at a production site,and compatibility with motion picture conventions. Because of the loadbearing and low friction characteristics of the compound crossed rollerslides 160, 180 and the crossed roller slide 140 in combination withmotors 810, 820 and 830 having characteristics of high speed, precisionand low acoustical and electromagnetic noise, a cinematographer mayrapidly acquire high quality audio-visual information.

The platform 100 provides for simultaneous active and/or manualinterocular control and convergence angle control. Moreover, thecinematographer is able to use the platform 100 to efficiently create astereoscopic experience that an audience can comfortably experience fora duration of a full length motion picture without the need forextensive post processing. More specifically, use of platform 100reduces the need to post process convergence for a given shot for adesired stereoscopic effect because a desired stereoscopic effect may beselected during image acquisition.

Closing Comments

The foregoing is merely illustrative and not limiting, having beenpresented by way of example only. Although examples have been shown anddescribed, it will be apparent to those having ordinary skill in the artthat changes, modifications, and/or alterations may be made.

Although many of the examples presented herein involve specificcombinations of method acts or system elements, it should be understoodthat those acts and those elements may be combined in other ways toaccomplish the same objectives. With regard to flowcharts, additionaland fewer steps may be taken, and the steps as shown may be combined orfurther refined to achieve the methods described herein. Acts, elementsand features discussed only in connection with one embodiment are notintended to be excluded from a similar role in other embodiments.

As used herein, “plurality” means two or more.

As used herein, a “set” of items may include one or more of such items.

As used herein, whether in the written description or the claims, theterms “comprising”, “including”, “carrying”, “having”, “containing”,“involving”, and the like are to be understood to be open-ended, i.e.,to mean including but not limited to. Only the transitional phrases“consisting of” and “consisting essentially of”, respectively, areclosed or semi-closed transitional phrases with respect to claims.

Use of ordinal terms such as “first”, “second”, “third”, etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having a same name (but for use of the ordinalterm) to distinguish the claim elements.

As used herein, “and/or” means that the listed items are alternatives,but the alternatives also include any combination of the listed items.

1. An method for acquiring stereoscopic images, comprising: mounting afirst camera to a first convergence plate, the first convergence platecoupled to a first plate by a first XY slide and by a first pivotdisplaced from the first XY slide adjusting a distance between the firstplate and a second plate to set an interocular distance between thefirst camera and a second camera rotating the first convergence plateabout the first pivot to set, at least in part, an angle of convergencebetween the first camera and the second camera.
 2. The method of claim1, wherein rotating the first convergence plate comprises controlling afirst motor coupled to the first XY slide.
 3. The method of claim 1,further comprising: mounting a second camera to a second convergenceplate, the second convergence plate coupled to the second plate by asecond XY slide and by a second pivot displaced from the second XY sliderotating the first and second convergence plates about the respectivefirst and second pivots to set the angle of convergence between thefirst camera and the second camera.
 4. The method of claim 3, whereinrotating the first and second convergence plates comprises controlling afirst motor coupled to the first XY slide and controlling a second motorcoupled to the second XY slide.
 5. The method of claim 4, wherein thefirst plate is connected to the second plate by a linear slide adjustinga distance between the first plate and a second plate comprisescontrolling a third motor coupled to the linear slide.
 6. An apparatussuited for use in stereoscopic image acquisition comprising: a basehaving a mounting device and a first plate attached to a second platevia a linear slide a first convergence plate adapted to affix a firstcamera, the first convergence plate attached to the first plate by afirst XY slide, the first convergence plate further attached to thefirst plate by a first pivot offset from the first XY slide.
 7. Theapparatus suited for use in stereoscopic image acquisition of claim 6,wherein the first plate is adapted to provide substantial mechanicalsupport to the first convergence plate and the first camera via thefirst XY slide.
 8. The apparatus suited for use in stereoscopic imageacquisition of claim 7 wherein the first XY slide is adapted to providesubstantial mechanical support to both the first convergence plate andthe first camera when the first convergence plate rotates about thefirst pivot.
 9. The apparatus suited for use in stereoscopic imageacquisition of claim 8 wherein the second plate is adapted to providesubstantial mechanical support to the first plate via the linear slidewhen the first plate is linearly displaced with respect to the secondplate.
 10. The apparatus suited for use in stereoscopic imageacquisition of claim 9 wherein the XY slide and the linear slide areadapted to restrict roll and tilt of the first camera while the firstplate is linearly displaced from the second plate and the firstconvergence plate is rotating about the first pivot.
 11. The apparatussuited for use in stereoscopic image acquisition of claim 6, furthercomprising: a first motor coupled to the first XY slide, the first motoradapted to rotate the first convergence plate about the first pivot. 12.The apparatus suited for use in stereoscopic image acquisition of claim6, further comprising: a second convergence plate adapted to affix asecond camera, the second convergence plate attached to the second plateby a second XY slide, the second convergence plate further attached tothe second plate by a second pivot offset from the second XY slide. 13.The apparatus suited for use in stereoscopic image acquisition of claim12, further comprising: a first motor coupled to the first XY slide, thefirst motor adapted to rotate the first convergence plate about thefirst pivot a second motor coupled to the second XY slide, the secondmotor adapted to rotate the second convergence plate about the secondpivot.
 14. The apparatus suited for use in stereoscopic imageacquisition of claim 13, further comprising: a third motor coupled tothe linear slide, the third motor adapted to displace the first platewith respect to the second plate.